What is the meaning of User-agent and Disallow in robots.txt file in wordpress

User-agent

They are Web Robots (also known as Web Wanderers, Crawlers, or Spiders), are programs that traverse the Web automatically. Search engines such as Google use them to index the web content, spammers use them to scan for email addresses, and they have many other uses.

Disallow

It tells the robots that it should not visit the pages or directory of site which are not allowed by this tag.

Details here

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)